Field of the Invention
The present invention relates to a wheel for vehicles and a method for manufacturing the same. More particularly, it relates to a wheel for vehicles which is capable of achieving superior design to a general steel wheel owing to design freedom obtained by a spoke-shaped disc, of achieving an increased natural frequency and rigidity while having the same level of a disc thickness and weight as the general steel wheel, and of achieving road noise reduction performance, and a method for manufacturing the same.
Description of Related Art
Recently, increased vehicle fuel efficiency and reduced noise during traveling have been demanded by vehicle users. In particular, advanced users prefer vehicles providing a more comfortable and low noise cabin.
Road noise of a real vehicle may be broadly divided into resonance noise, booming noise, and rumble noise. Thereamong, resonance noise is introduced to a vehicle cabin as vibration applied from a road surface during traveling is transmitted to, for example, tires, wheels, chassis components, and a vehicle body.
Various specifications of wheels for vehicles have been developed to improve road noise.
Generally, wheels for vehicles may be divided into steel wheels formed of steel and aluminum wheels formed of an aluminum alloy.
FIG. 1A is a view illustrating a conventional general steel wheel for vehicles, and FIG. 1B is a view illustrating a conventional aluminum wheel.
The steel wheel is manufactured by bonding a steel rim 1 and a disc 2 to each other via welding and has advantages of low price and easy manufacture. However, the steel wheel is inferior in design and heavier as compared to an aluminum wheel due to characteristics of steel and a processing method including welding.
The aluminum wheel is manufactured using an aluminum alloy without welding such that a rim 1 and spokes 3 are integrally formed. The aluminum wheel has advantages including superior design and marketability and light weight, but also has disadvantages including low productivity and high price due to characteristics of an aluminum alloy and a complicated processing method.
In recent years, to improve design of a conventional general steel wheel, a styled steel wheel having a spoke-shaped disc similar to an aluminum wheel has been developed. This styled steel wheel increases marketability of a vehicle through improvement in wheel design.
Prior art discloses a wheel for vehicles in which a rim is formed of steel and a disc is formed of an aluminum alloy for improvement of design, and a styled steel wheel which is manufactured by welding a spoke-shaped disc having spokes and decorative holes (or vent holes) to a rim.
In addition, prior art discloses an aluminum wheel for vehicles which includes a rim consisting of a cylindrical base rim configured to face the tread of a tire and a support rim integrally protruding from an outer surface of the base rim in the circumferential direction of the base rim, the support rim and the base rim having a hollow region interposed therebetween.
The aluminum wheel having the hollow region is capable of absorbing and reducing resonance noise generated from the tire via the hollow region of the rim even if a separate sound absorption material is not used, thereby advantageously reducing noise to be transmitted to a vehicle cabin.
Meanwhile, FIG. 2 illustrates vibration in a steel wheel rim mode. A general steel wheel is known as generating greater road noise by about 2 dB to 3 dB as compared to an aluminum wheel. This is because the natural frequency of the steel wheel rim mode is within a range of 170 Hz to 200 Hz that is greatly lower than that (within a range of 300 Hz or more) of an aluminum wheel.
The aforementioned styled steel wheel may increase the natural frequency owing to design freedom as to the structure and shape of a disc supporting a rim, which may cause performance improvement in terms of design and road noise.
However, the styled steel wheel needs to increase a disc thickness in order to achieve a high natural frequency and such a thicker disc than that of a conventional wheel causes an excessive wheel weight.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.